A coating of liquid precursor containing a metal is applied to a first electrode, baked on a hot plate in oxygen ambient at a temperature not exceeding 300.degree. C. for five minutes, then RTP annealed at 675.degree. C. for 30 seconds. The coating is then annealed in oxygen or nitrogen ambient at 700.degree. C. for one hour to form a thin film of layered superlattice material with a thickness not exceeding 100 nm. A second electrode is applied to form a capacitor, and a second anneal is performed in oxygen or nitrogen ambient at a temperature not exceeding 700.degree. C. If the material is strontium bismuth tantalate, the precursor contains u mole-equivalents of strontium, v mole-equivalents of bismuth, and w mole-equivalents of tantalum, where 0.8.ltoreq.u.ltoreq.1.0, 2.0.ltoreq.v.ltoreq.2.3, and 1.9.ltoreq.w.ltoreq.2.1.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of fabricating a thin film of layered superlattice material comprising: providing a substrate, and a precursor containing metal moieties in effective amounts for spontaneously forming a layered superlattice material upon heating said precursor; applying said precursor to said substrate to form a coating; and heating said coating at a temperature not exceeding 700.degree. C. for a total time not exceeding two hours to form said thin film of layered superlattice material on said substrate.
2. A method as in claim 1, wherein said heating comprises a step of baking said coating on said substrate at a temperature not exceeding 300.degree. C.
3. A method as in claim 2, wherein said step of baking is conducted in an oxygen-enriched ambient.
4. A method as in claim 3, wherein said step of baking is conducted in O.sub.2 gas.
5. A method as in claim 3, wherein said step of baking is conducted for a time period not exceeding 15 minutes.
6. A method as in claim 1, wherein said heating comprises a step of rapid thermal processing said coating.
7. A method as in claim 6, wherein said step of rapid thermal processing is conducted at a temperature not exceeding 675.degree. C.
8. A method as in claim 6, wherein said step of rapid thermal processing is conducted for 30 seconds with a ramping rate of 100.degree. C. per second.
9. A method as in claim 1, wherein said heating comprises a step of annealing said coating at a temperature not exceeding 700.degree. C.
10. A method as in claim 9, wherein said step of annealing is conducted for a time period not exceeding one and one-half hours.
11. A method as in claim 9, wherein said step of annealing is conducted in an oxygen-enriched ambient.
12. A method as in claim 9, wherein said step of annealing is conducted in an oxygen-deficient ambient comprising nitrogen.
13. A method as in claim 12, wherein said step of annealing is conducted in substantially pure N.sub.2 gas.
14. A method as in claim 1, wherein said substrate comprises a first electrode, and further comprising steps of forming a second electrode on said coating, after said step of heating, to form a capacitor, and subsequently performing a step of post-annealing.
15. A method as in claim 14, wherein said first electrode and said second electrode each comprise platinum and titanium.
16. A method as in claim 14, wherein said step of post-annealing is conducted at a temperature not exceeding 700.degree. C. for a time period not exceeding 30 minutes.
17. A method as in claim 16, wherein said step of post-annealing is conducted in an oxygen-enriched ambient.
18. A method as in claim 17, wherein said step of post-annealing is conducted in an oxygen-deficient ambient comprising nitrogen.
19. A method as in claim 18, wherein said step of post-annealing is conducted in substantially pure N.sub.2 gas.
20. A method as in claim 1, further comprising forming an electrically conductive barrier layer on said substrate prior to said applying said precursor.
21. A method as in claim 1, wherein said heating comprises steps of baking said coating, rapid thermal processing said coating, annealing said coating, and post-annealing said coating.
22. A method as in claim 1, wherein said thin film has a thickness not exceeding 90 nm.
23. A method as in claim 1, wherein said thin film has a thickness not exceeding 50 nm.
24. A method as in claim 1, wherein said layered superlattice material comprises strontium bismuth tantalate.
25. A method as in claim 1, wherein said precursor includes u mole equivalents of strontium, v mole-equivalents of bismuth, and w mole-equivalents of tantalum, and 0.8.ltoreq.u.ltoreq.1.0, 2.0.ltoreq.v.ltoreq.2.3, and 1.9.ltoreq.w.ltoreq.2.1.
26. A method as in claim 25, wherein u=0.9, v=2.18.
27. A method as in claim 1, wherein said layered superlattice material comprises strontium bismuth tantalum niobate.
28. A method as in claim 1, wherein said precursor includes u mole-equivalents of strontium, v mole-equivalents of bismuth, w mole-equivalents of tantalum, and x equivalents of niobium, and 0.8.ltoreq.u.ltoreq.1.0, 2.0.ltoreq.v.ltoreq.2.3, 1.9.ltoreq.w.ltoreq.2.1, 1.9.ltoreq.x.ltoreq.2.1 and 1.9.ltoreq.(w+x).ltoreq.2.1.
29. A method as in claim 28, wherein u=0.9, v=2.18.
30. A method of fabricating a thin film of layered superlattice material comprising: providing a substrate, and a precursor containing metal moieties in effective amounts for spontaneously forming a layered superlattice material upon heating said precursor; applying said precursor to said substrate to form a coating; and baking said coating on said substrate at a temperature not exceeding 300.degree. C. in an oxygen-enriched ambient.
31. A method as in claim 30, wherein said oxygen-enriched ambient is substantially pure O.sub.2 gas.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 11, 1999
June 12, 2001
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